The present invention relates to a self-locking reduction device in which rotational force from an input shaft is surely transmitted to output means, while rotational force from the output means is prevented from being transmitted to the input shaft.
In a known spur-gear-type reduction device used in a winch, it is impossible to prevent rotational force from being transmitted to an input shaft without additional braking means.
In a worm-gear-type reduction device, by determining a lead angle less than a friction angle of a tooth surface, self-locking can be made at some extent. But, coefficient of friction can be less than expected value owing to sliding speed, vibration, running feature and lubrication to cause slacking accident and unreliable self-locking.
The inventor invented a reliable self-locking reduction device using a micro-tooth-number-difference composite hypocycloid which has two-step internal gear mechanism, and filed it as Japanese Patent Application No.11-210793 (Pub.No.2001-41293).
This reduction device was developed to have high reduction ratio of more than 40:1. But it is required to provide a reliable simplified self-locking reduction device having low reduction ratio of 8:1 to 40:1.
It is an object of the invention to provide a reliable self-locking small high-functional reduction device and a winch in which it is used.